Potash extraction.



E. L. ANDERSON.

POTASH EXTRACTION.

APPLICATION FlLED APR. 8, 191a.

Patented Jan. 15, 1918.

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INVENTQR WITNESSES ears rarer-a canton EDWARD L. ANDERSON, 0FPITTSBURGH, PENNSYLVANIA.

POTASH EXTRACTION.

Specification of Letters Patent.

Patented Jan. 15, 19118.

Application filed April 8, 1916. Serial No. 89,782.

To all 'wlwmc't may concern:

Be it known that I, EDWARD In ANDERSON, a citizen of the United States,and resident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented certain new and useful Improvements inPotash Extraction, of which the following and exact description, refing,forming part of this specification, which shows 'a vertical section ofone form of apparatus for carrying out my method.

The invention relates to potash extraction and more particularly to theprocess of extracting potash from feldspar or the like by electrolysis.

Various attempts have been made to decompose feldspar or the likematerial by electro-chemical methods, but all have proven too costly duein part to the fact that the feldspar being of such high electricalresistance the amount of electrical energy necessary to bring about thedecomposition of the feldspar was so great as to prove unprofitable on acommercial basis.

I have discovered that feldspar or the like material may be decomposedby electrochemical means with a relatively small amount of electricalenergy by first mixing an insoluble conductive material, such as carbonor a carbon compound, so as to make the mixture a conductor ofelectricity. This is preferablyaccomplished by finely grinding thefeldspar and mixing it with a certain amount of finely ground carbon.Similar results may be obtained by mixing finely ground feldspar withcrude oil, then heatin the mixture to a red heat out of contact with theair so as to deposit on each particle of feldspar a conducting film ofcarbon.

I have also discovered that the extraction of potash is greatlyfacilitated by subjecting the feldspar thus prepared to the action of anelectric current in a solution contain-' current liberating siliconfluorid which breaks down the insoluble feldspar combinlng with thepotash to form an easily electrolyzable potash compound.

The preferred method of procedure is described as follows, referencebeing had to the illustrated embodiment of my apparatus.

A vessel 1 is divided into two compart ments 2 and 3 by means of aporous partition 4 of unglazed clay or carbon. In the drawing thisporous partition is shown in the form of an inner cup placed within theouter vessel 1. The compartment 2 forms an anode compartment in which isplaced a carbon electrode 5. The other compartment 3 forms a cathodecompartment in which is placed a copper or carbon electrode 6.

The feldspar or similar material is finely ground, mixed with carbon,and packed in the anode compartment, the mixture of feldspar and carbonbeing indicated by reference numeral 7. The mixture is saturated withWater containing five or ten per cent. of

' hydrofluorsilicie acid, or hydrofluoric acid which in a short timewill be converted by the reactions into hydrofluorsilicic acid.

The cathode compartment 3 is filled with water. A direct current ispassed through the cell from the anode 5 to the cathode 6. The carbonmixed with the feldspar renders such mixture conducting and allows thecurrent to flow through the body of pulverized feldspar which wouldotherwise have a high electrical resistance.

The action of the electric current is to decompose the feldsparproducing potassium hydroxid in the cathode compartment and a mixture ofaluminum oxid and silica in the anode compartment.

The following reactions are believed to take place in the cell: Thehydrofluorsilicic acid is decomposed by the current, liberating sili--is electrically. decomposed to yield silicon fluorid which decomposes afresh supply of feldspar. The aluminum fluorsilicate thus formed isreadily decomposed producing silicon fluorid, aluminum oxid and silica.The silicon 'fluorid like that produced by the decomposition of thepotassium fluorsilicate goes through the cyclic reaction to combine withthe fresh supply of feldspar. The aluminum oxid and silica remain in theanode compartment. The following equations are believed to express thereactions taken place in the cell:

K SiF (upon electrolysis):2K,OH (at cathode) |SiF +2HF (at anode).

z q (upon electrolysis):

' A1,0 +SiF,+2HF.

The potash which is recovered in the cathode compartment in the form ofpotassium hydroxid may be drawn off from time to time,boiled to dryness,when it is ready for the market. At the end of the operation thecontents of the anode compartment are removed and the hydrofluorsilicicacid is washed out and reused. The mixture of aluminum oxid, silica andcarbon removed from the anode compartment are separated by any suitableseparation method. The aluminum oxid and silica form valuableby-products. The aluminum oxid may be used in the manufacture ofabrasives or reduced by any of the well known methods of making themetal aluminum. The silica produced is of a fine white texture and isvaluable for use in paint, paper and other industries. The carbon, afterbeing separated from the mixture, may be again used for a fresh chargeof feldspar.

By the term feldspar or the like I intend to include feldspar or likepotash containing materials including orthoclase, microclin, cerecite,granites and various other potash containin rocks. It is obvious thatthe method may e practised with forms of apparatus other than thatillustrated in the drawing and that certain modifications in the methodmay be employed within the scope of the following claims.

I claim:

1. Those steps in the process of extracting potash from feldspar or thelike, which consist in grinding it and mixing it with an insolubleelectrically conductive material, and in subjecting the mixture to theaction of an electric current.

2. Those steps in the process of extracting potash from feldspar or thelike, which consist in grinding it and mixing it with an insolubleelectrically conductive material, and

in subjecting the mixture to the action of an electric current in asolution containing a substance which combines with the potash toconvert it into an easily electrolyzable form.

- 3. Those steps in the process of extracting potash from feldspar orthe like, which consist in grinding it and mixing it with carbod, andsubjecting the mixture to the action of an electric current.

4. Those steps in the process of extracting potash from feldspar or thelike, which consist in grinding it and mixing it with carbon, andsubjecting the mixture to the action of an electric current in asolution containing a substance which combines with the potash toconvert it into an easily electrolyzable form.

In testimony whereof I have hereunto set my hand. EDWARD L. ANDERSON.Witnesses:

GEo. E. STEBBINS, H. M. CQRWIN.

